<!DOCTYPE html>
<style>
#a, #c {
    width:25px;
    height:50px;
    float: left;
}
</style>
<p>There should be a green <em>square</em> below.</p>
<div>
    <div id="a" style="background: green;"></div>
    <div id="b">
    </div>
    <div id="c" style="background: red;">
        <div style="float: left; width: 25px; height: 50px; background: green;"></div>
    </div>
</div>
<script>
document.body.offsetTop;
document.getElementById('b').style.display = 'inline-block';
</script>
